The present invention relates to a balise for remotely communicating a signalling message, the balise intended to be arranged along a railway track in order to communicate with a communication device on board a vehicle running on the railway track or with a configuration device. The balise comprises means for receiving an activation signal originating from the onboard communication device, means for transmitting to the onboard communication device a signalling signal carrying the signalling message, at least one information storage means, and control means able to save data in the information storage means.
Balises are known that are arranged along a transport track and able to remotely communicate signalling information, such as, for example, the maximum speed limit that must not be exceeded, with communication devices on board transport vehicles.
Various types of balises exist, each adapted to communicate with a complementary type of onboard communication device. Each type of balise is configured according to a given standard and is able to communicate only with a complementary type of communication device configured according to the same standard.
The standards define the specifications of the signals exchanged and the type of coding for the signalling message.
However, these standards are different in each European country. Furthermore, a communication device of one type cannot decode signalling messages transmitted by a balise of another type. For example, in France, balises and associated onboard communication devices meet the specifications of the "KVB" (balise speed control) standard.
For onboard communication devices to be able to communicate with balises in different countries, the European Community has drawn up a standard called the "Eurobalise" standard which defines the shape of the signals and the coding of the signalling message which are exchanged between a "Eurobalise" type balise and a "Eurobalise" type communication device. This standard is applied in some European countries, but is not yet mandatory.

The "Eurobalise" standard defines the "Eurobalise" type signal. The standard is publicly accessible, in particular via the document entitled "SUBSET 036 Version 2.3.0 (FFFIS for Eurobalise)" available at the following Internet address: "http://www.aeif.org/ccm/default.asp" in the "Documents" section.
The Eurobalise type signal is a pure sinusoid of frequency 27.095 MHz.
"Eurobalise" type balises are designed to not respond automatically to signals transmitted by previous generation onboard equipment. However, there are at least three scenarios in which the balise must not respond to onboard communication devices:
a) For temporary speed limits: when work is taking place on the tracks, balises are installed temporarily so as to lower the authorised speed limit. Since such work progresses intermittently, the balises must be silent when no work is taking place and they must transmit when work is taking place.
b) When balises are being installed: balises can be installed before the messages that they must communicate are ready. If an onboard communication device tries to read the message that is theoretically recorded in the balise, the balise transmits incomprehensible data. By making them silent, lengthy installation phases can progress without needing to wait until the message creation activities are completed. Therefore the balises must be silent while the messages are not implemented such that trains equipped with "Eurobalise" type communication devices are not disrupted by receiving false messages.
c) For activities to check programmed data: certain teams program the
messages to be implemented in the balises and other teams check that the correct
messages are implemented in the correct balises. Between these two operations, the
trains must not receive messages since those messages have not yet been checked.
To switch to "silent" mode, a metal plate must be placed manually on each balise to physically prevent any signal transmission.
However, the manual operation to switch to "silent" mode exhibits a number of drawbacks. The placing of this plate is a long process and requires either that the teams are made to work between two trains at times when the traffic level is less, orthat the track, and therefore the railway traffic, is blocked. Furthermore, access to the balises is not always easy either because the track is in a mountainous region, or because the track is far away from any road, such an access able to pose risks to staff. Lastly, physically preventing transmission of signalling messages is not a reliable solution since, if the plate is stolen, there is no longer any device preventing the balise from transmitting signalling messages to the devices placed on board vehicles running on the track.
Furthermore, when the balises must be switched to "transmit" mode, the operation is carried out manually: the staff must access each of the balises in order to remove the metal plate with the same drawbacks as for switching to silent mode.
An object of the present invention is to overcome these drawbacks by proposing a balise and a configuration device which is quick to configure, which does not put the safety of staff at risk and which does not transmit untimely signals.
To this end, a subject of the invention is a balise, of the abovementioned type, for remotely communicating a signalling message, characterised in that the reception means are also able to receive a configuration signal containing a configuration message originating from the configuration device, the configuration message defining an operating mode of the balise from among a "transmit" mode or a "silent" mode, and in that the information storage means is able to contain the operating mode contained in the configuration message.
Thus, untimely signals are avoided since preventing or allowing transmission is not linked to a physical item present on the casing of the balise. The balise according to the invention also provides for reducing the quantity of metallic material required to prevent signal transmissions since a plate is no longer required. The balise according to the invention is consequently more economical and more reliable than a balise of the prior art.
The balise can also have one or more of the following features:
- the control means are able to determine at least one parameter of the received configuration signal,
- the control means are able to determine two parameters of the received
configuration signal, the parameters comprising the consecutive periods of the
received configuration signal,
- the control means are able to reconstruct the configuration message contained in the configuration signal,
- the control means are able to control the saving of the configuration in the information storage means according to the result of the comparison made of the reconstructed configuration message, and to control the transmission of the signalling signal carrying the signalling message according to the configuration saved in the information storage means,
- the control means prevent the transmission means from transmitting the signalling message carrying a signalling message to the vehicle when the balise is configured in "silent" mode, regardless of the activation signal transmitted by the onboard communication device,
- the control means allow the transmission means to transmit the signalling message carrying a signalling message to the vehicle when the balise is configured in "transmit" mode and when the activation signal transmitted by the onboard communication device is of the "Eurobalise" type.
The invention relates also to a configuration device for a communication balise according to the invention including means for modulating the configuration signal carrying the configuration message intended to be saved in the balise.
The configuration device according to the invention exhibits the advantage of configuring the balises extremely rapidly since no manual intervention on each balise is necessary. When the configuration device is on board a vehicle, the time to configure balises is reduced to the minimum, i.e. to the time required by the vehicle with the configuration device to cover the line on which the balises are arranged. The safety of staff is greatly improved since the staff are no longer on the railway track.
The configuration device can have one or more of the following features:
- the configuration signal is a sinusoid that is amplitude-modulated so as to carry the configuration message,
- the configuration message includes a frame formed by bits at "1" and by bits at "0",
- a bit at "1" is defined by a series of pulses of maximum amplitude and of a first period, followed by a series of pulses of minimum amplitude and of a second period that is different from the first period,
- a bit at "0" is defined by a series of pulses of maximum amplitude and of a first period, followed by a series of pulses of minimum amplitude and of a third period that is different from the second period.
The invention will be better understood on reading the following description given purely by way of example and with reference to the drawings in which:
- Figure 1 is a schematic view of the communication between a
communication device placed on board a vehicle and a balise according to the
invention, arranged along a railway track,
- Figure 2 is a schematic view of a balise according to the invention, arranged along a railway track, being configured by a configuration device placed on board a vehicle,
- Figure 3 is a block diagram of a balise according to one embodiment of the invention,
- Figure 4 is a representation of a configuration signal SC.
The balise according to the invention is illustrated schematically in Figure 1 and in Figure 2. In Figure 1, the balise 1 is arranged along a transport track 4, on which a vehicle 3 runs with an onboard communication device 5 able to transmit an activation signal S1 to the balises 1. When the balise 1 is operating in "transmit" mode, it returns to the onboard communication device 5 a signalling signal S2 carrying a signalling message M.
The balise 1 can be configured as many times as necessary over time by the passing of the configuration device 2, in order to be switched to "silent" mode or back to "transmit" mode. Figure 2 schematically illustrates the balise 1 being configured by a configuration device 2 placed in a vehicle 3'. When close to a balise, the position of which is known geographically, the configuration device 2 transmits a configuration message SC containing a configuration message MC able to configure the balise to be in "silent" mode or in "transmit" mode.
The balise 1 is illustrated in Figure 3. The balise 1 comprises a casing 10 containing an antenna 12, transmission means 14 and energising means 16 connected to the antenna 12.
The antenna 12 is intended to receive the configuration signal SC containing the configuration message MC sent by the configuration device 2 or is intended to receive the activation signal S1 sent by the onboard communication device 5. The antenna 12 is also intended to transmit the configuration message MC to the control means 18 or to transmit a signalling signal S2 of the Eurobalise type to the onboard communication device 5.
The energising means 16 are intended to retrieve the electrical energy contained in the activation signal S1 in order to power the electronic components of the balise 1.
The transmission means 14 are formed by a modulator/demodulator intended to amplitude-modulate or frequency-modulate the signalling signal S2 and to transmit it to the antenna 12 for broadcast. The transmission means 14 are also intended to demodulate the configuration signal SC and to transmit it to the control means 18 for processing.
The control means 18 are intended to control the transmission means 14 in order that the latter amplitude-modulate or frequency-modulate the signalling signal S2 carrying the signalling message M. The control means 18 are also intended to process the configuration signal SC in order to interpret the configuration message MC by comparing it with standard messages implemented in the control means 18. The control means 18 are formed, for example, by a computer implemented in an ASIC or an FGPA.
The control means 18 are connected, on the one hand, to a first information storage means, for example a memory, referred to hereafter in the description as configuration memory 20. The control means 18 are able to save in the configuration memory 20 the configuration contained in the configuration message MC received in order to assign this configuration to the balise 1. The configuration is either the "silent" mode or the "transmit" mode.
The control means 18 are connected, on the other hand, to a second information storage means 22, for example a memory, referred to hereafter in the description as second memory, and are intended to save or retrieve a signalling message M in this second memory 22.
The second memory 22 is able to store one or more signalling messages M intended to be transmitted to the communication device 5 placed in the vehicle 3 for the case in which the balise 1 is in "transmit" mode. This message contains, for example, the location of the balise and the maximum speed that must not be exceeded. It is either transmitted periodically to the balise 1 by central signalling equipment 40 via ground-based equipment (not represented), or permanently stored in the second memory 22 in the time prior to the installation, or during the installation, of the balise.
The retrieval module 24 is intended to retrieve a signalling message M, to format it by modifying its electrical format, and to send it to the control means 18 which send it to the transmission means 14 or save it in the second memory 22.
According to a variant embodiment, the configuration memory 20 and the second memory 22 form only one single storage means.
The configuration signal SC transmitted to the balises is obtained from an amplitude modulation of a sinusoid having a frequency of 27.095 MHz. Figure 4 illustrates the configuration signal SC sent to the balise 1.
The sinusoid is amplitude-modulated. The configuration signal SC is represented in Figure 4 and comprises, for example, a series of pulses of a period P1 and of maximum amplitude (100%) and a series of pulses of a period P2 or P3, different from P1, and of an amplitude that is less than half (50%) the maximumamplitude, referred to as troughs. The period P2 is shorter than the period P3. For example, P1 is a period of 20 us, P2 is a period of 2 us and P3 is a period of 3 us.
The configuration signal SC thus comprises a series of pulses and troughs which represent the frame of the configuration message MC. In the configuration device according to the invention, a bit equal to "1" is represented by a series of pulses of a period P1 followed by a series of troughs of a period P2, i.e. a period P of value 22 us, and a bit equal to "0" is represented by a series of pulses of a period PI followed by a series of troughs of a period P3, i.e. a period P' of value 23 us. The shape of the configuration signal S1 is illustrated in Figure 2. The period P2 or P3 of the troughs therefore provides for defining whether the bit is equal to "1" or equal to "0".
The European standard already defines a signal of a shape identical to the configuration signal SC having, alternately, the periods "P1P2-P1P3-P1P2-P1P3...". Producing a configuration signal having this form of alternating periods enables the reuse of already-existing functional blocks in the designs of the balises 1 and of their configuration device 2.
Other configuration signals are capable of producing this same function, the drawback being that it is then necessary to create new functional blocks in the balise. Reusing the signal of the European standard avoids creating new electronic blocks, the only item affected being the software of the control unit.
It thus becomes possible to transmit a configuration message through a configuration signal SC to a baiise which includes the necessary means to decode this signal SC.
The frame of the configuration message is made up of a header, an objective of which is to inform the balise that a message is going to be sent to it, and the actual message. This message is the instruction to switch to "silent" mode or to "transmit" mode.
The header and the message are represented by a predefined sequence of bits. A frame is, for example, made up of 15 bits, five bits being reserved for the header and 10 bits being reserved for the message.
For example, the header may be defined as being "10010", the message to switch to "silent" mode may be defined as being "1110001111" and the message to switch to "transmit" mode may be defined as being "1010100010". The configuration signal SC will therefore be amplitude-modulated so as to represent these 15 bits, "100101110001111" indicating to the balise to switch to "silent" mode, "100101010100010" indicating to the balise to switch to "transmit" mode.
The configuration method is as follows: the configuration device 2 is moved on the track 4 - either manually or by being on board a vehicle 3' - and it transmits to each balise 1 an amplitude-modulated configuration signal SC containing a configuration message MC. The configuration signal SC is received by the antenna 12 of the balise 1. The antenna 12 transmits the signal SC to the transmission means 14 which demodulate it, reconstruct its envelope and send it to the control means 18.
The control means 18 measure the periods of the troughs and deduce from this whether the bits are at "1" or at "0". The signalling message MC is reconstructed and is compared with the standard messages saved beforehand in the control means 18. If the configuration message MC is of the "silent" or "transmit" type, the control means 18 save the configuration message MC in the configuration memory 20.
When a vehicle 3 running on the track 4 comes close to a balise 1, the onboard communication device 5 transmits an activation signal S1. This signal S1 is received by the antenna 12 and transmitted to the control means 18 via the transmission means 14.
The control means 18 are intended to search in the configuration memory 20 for the configuration assigned to the balise 1. To this end, the control means 18 are able to compare the configuration message MC contained in the configuration memory 20 with the two configuration messages corresponding to the "silent" mode and "transmit" mode which are stored in memory in the control means 18.
When the balise 1 is configured in "silent" mode, regardless of the activation signal S1 transmitted by the onboard communication device 5, the control means 18 prevent the transmission means 14 from transmitting a signalling message S2 to the vehicle 3.
When the balise 1 is configured in "transmit" mode, the control means 18 allow the transmission means 14 to transmit a signalling message S2 to the vehicle 3, if the activation signal S1 is of the "Eurobalise" type.
Thus, when the configuration message MC stored in the configuration memory 20 corresponds to the "transmit" mode and when the activation signal S1 is of the "Eurobalise" type, the control means 18 are intended to retrieve the signalling message M contained in the second memory 22 or originating from the retrieval module 24. This signalling message M is then transmitted to the transmission means 14 and then to the antenna 12, which transmits to the onboard communication device 5 a signalling signal S2 coded according to the "Eurobalise" standard and comprising the signalling message M.
The configuration of the balise 1 is set up to be modified upon receiving a second configuration message MC.
To modify the configuration of the balise 1, the configuration device 2 transmits a second configuration signal SC containing a second configuration message MC, received by the control means 18 via the antenna 12.
The control means 18, upon receiving this message MC, are intended to save in the configuration memory 20 the new configuration contained in the configuration message MC in place of the configuration which is stored therein, by processing the second configuration signal SC in the same way as the first configuration signal SC.
As a variant, the balise is configured at the workshop before being placed along the track. The configuration device 2 is then carried by the operators.
As a variant, the configuration device 2 is able to be connected by a wired link to the balise 1.

CLAIMS
1. A balise (1) for remotely communicating a signalling message (M), the
balise (1) intended to be arranged along a railway track (4) in order to communicate
with a communication device (5) on board a vehicle (3) running on the railway track
(4) or with a configuration device (2), comprising:
- means (12) for receiving an activation signal (S1) originating from the onboard communication device (5),
- means (14) for transmitting to the onboard communication device (5) a signalling signal (S2) carrying the signalling message (M),

- at least one information storage means (20, 22),
- control means (18) able to save data in the information storage means (20), characterised in that:

- the reception means (12) are also able to receive a configuration signal (SC) containing a configuration message (MC) originating from the configuration device (2), the configuration message (MC) defining an operating mode of the balise (1) from among a "transmit" mode or a "silent" mode,
- the information storage means (20, 22) is able to contain the operating mode contained in the configuration message (MC).
2. A balise (1) according to Claim 1, characterised in that the control means (18) are able to determine at least one parameter of the received configuration signal (SC).
3. A balise (1) according to either Claim 1 or Claim 2, characterised in that the control means (18) are able to determine two parameters of the received configuration signal (SC), the parameters comprising the consecutive periods of the received configuration signal (SC).

4. A balise (1) according to Claim 3, characterised in that the control means, (18) are able to reconstruct the configuration message (MC) contained in the configuration signal (SC).
5. A balise (1) according to Claim 4, characterised in that the control means (18) are able to compare the configuration message (MC) with two configuration messages, corresponding to the "silent" mode and the "transmit" mode, which are stored in memory in the control means (18).
6. A balise (1) according to Claim 5, characterised in that the control means (18) are able to control the saving of the configuration in the information storage means (20, 22) according to the result of the comparison made of the reconstructed configuration message, and to control the transmission of the signalling signal (S2) carrying the signalling message (M) according to the configuration saved in the information storage means (20, 22).
7. A balise (1) according to Claim 6, characterised in that the control means (18) prevent the transmission means (14) from transmitting the signalling message (S2) carrying a signalling message (M) to the vehicle (3) when the balise (1) is configured in "silent" mode, regardless of the activation signal (S1) transmitted by the onboard communication device (5).
8. A balise (1) according to Claim 6, characterised in that the control means (18) allow the transmission means (14) to transmit the signalling message (S2) carrying a signalling message (M) to the vehicle (3) when the balise (1) is configured in "transmit" mode and when the activation signal (S1) transmitted by the onboard communication device (5) is of the "Eurobalise" type.
9. A configuration device (2) for a communication balise (1) defined according
to any one of the preceding claims, characterised in that the configuration device (2)
includes means for modulating the configuration signal (SC) carrying the
configuration message (MC) intended to be saved in the balise (1).
10. A configuration device (2) for a balise (1) according to Claim 9,
characterised in that the configuration signal (SC) is a sinusoid that is amplitude-
modulated so as to carry the configuration message (MC).
11. A configuration device (2) for a balise (1) according to either Claim 9 or
Claim 10, characterised in that the configuration message (MC) includes a frame
formed by bits at "1" and by bits at "0".
12. A configuration device (2) for a balise (1) according to Claim 11, characterised in that a bit at "1" is defined by a series of pulses of maximum amplitude and of a first period (P1), followed by a series of pulses of minimum amplitude and of a second period (P2) that is different from the first period (P1).
13. A configuration device (2) for a balise (1) according to Claim 12, characterised in that a bit at "0" is defined by a series of pulses of maximum amplitude and of a first period (P1),'followed by a series of pulses of minimum amplitude and of a third period (P3) that is different from the second period (P2).